# Need help understanding relative velocity problem

Shindo

## Homework Statement

The escalator that leads down into a subway station has a length of 30.0 meters and a speed of 1.8 meters/second. relative to the ground. A student is coming out of the station by running in the wrong direction on this escalator. The local record time for this trick is 11 seconds. Relative to the escalator what speed must the student exceed in order to beat the record?

My question: I don't understand what this question is asking. What does it mean by "running the wrong direction on this escalator"? Any help on what this question is asking, and what I need to find is very appreciated.

Staff Emeritus
Homework Helper

## Homework Statement

The escalator that leads down into a subway station has a length of 30.0 meters and a speed of 1.8 meters/second. relative to the ground. A student is coming out of the station by running in the wrong direction on this escalator. The local record time for this trick is 11 seconds. Relative to the escalator what speed must the student exceed in order to beat the record?

My question: I don't understand what this question is asking. What does it mean by "running the wrong direction on this escalator"? Any help on what this question is asking, and what I need to find is very appreciated.

Welcome to PF.

The "wrong" direction means that the person is running on the escalator in the opposite direction that the escalator is moving. Normally, a person would either stand on the escalator and move in with the same speed and the same direction as the escalator, OR walk on the escalator in the same direction that the escalator is already moving.

Shindo
The "wrong" direction means that the person is running on the escalator in the opposite direction that the escalator is moving.

Okay, but just to clarify, the question is asking how fast the person needs to run a 30 meter distance, with 1.8 m/s of force AGAINST him; all that it is faster than 11 seconds?

Staff Emeritus